


Schrödinger's Elemental

by gREat_unreST



Category: Undertale (Video Game)
Genre: Awkward Flirting, Established Relationship, M/M, because that's how gaster rolls, grillby is much better at it, the flirting part not the quantum mechanics, using quantum mechanics metaphors
Language: English
Status: Completed
Published: 2020-10-26
Updated: 2020-10-26
Packaged: 2021-03-08 18:49:01
Rating: General Audiences
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 1,140
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/27211486
Author URL: https://archiveofourown.org/users/gREat_unreST/pseuds/gREat_unreST
Summary: In which Gaster contemplates the anatomy and physiology of a fire elemental, while Grillby is just lazy.A short Grillster fic.
Relationships: W. D. Gaster/Grillby
Kudos: 36





	Schrödinger's Elemental

It was after hours at Grillby's. Gaster was sitting at the bar, observing Grillby as the bartender cleaned glassware. His gaze was drawn to the elemental's glasses. He knew hidden behind all the light reflected on the glasses were Grillby's eyes.

What would it be like to catch him unawares and take off those glasses? Gaster stifled a laugh behind his hand. Would Grillby's eyes dart around unfocused, trying to see where his glasses went? Or would it reveal a dashing face with smouldering eyes, unfazed by the antics of a mischievous skeleton? Heat spread across his face and his other hand shot up to better hide his blush. He had a hypothesis to test.

"Grillby!" he called out, grabbing the elemental's attention. He signed as he spoke, "Come here for a second."

Grillby placed the glass on the counter and walked over. The moment he was in range, Gaster reached out and deftly plucked the glasses from the elemental's face, leaving Grillby no time to react at all. And the skeleton saw...

Fire. Bright orange fire curling down into a vague jawline and neck. Flames flickering over where a face should be, but no eyes or mouth or any facial features in sight. Until two horizontal slits of light, slightly brighter than the surrounding flames, shimmered into existence at the middle. It gradually thickened and blinked, forming a pair of shining white eyes that burnt curiously at the silent skeleton.

"Were your eyes closed the entire time?" Gaster exclaimed.

Grillby's eyes crinkled in confusion. "...No? They just were not there when you took my glasses off."

Gaster paused. Then he gaped, hands signing incredulously, " _You didn’t have eyes?_ "

The elemental sighed, though there was a hint of fondness in his exasperation. "No, Gaster. I just sometimes get lazy about showing my eyes when I have glasses on. Others can hardly see my eyes past the glass anyway when there is so much light reflecting around it." He winked. "I’m a being of fire and magic. Just because you cannot see my eyes doesn't mean I am not looking at you."

"Oh," Gaster hummed contemplatively. Interesting. He had assumed Grillby's eyes would always be visible because whenever the glasses were off, he would see those two white slits blinking back at him. The only times Gaster thought he had observed their absence were when the elemental was asleep, the white slits disappearing as if covered by eyelids.

Wait. Grillby's words played through his mind again. _I am looking at you when you do not notice._ "O-oh," he stammered, no hands covering his blush this time.

Grillby crackled a laugh and plucked the glasses out of Gaster's boneless ( _hah_ ) fingers, putting them back on. As always there were no discernible nose or ears for the glasses to perch on. They just sat nicely where they were supposed to be. Magic.

His eyes were covered again, but Gaster knew the elemental was smiling because he had parted his lips slightly to let the bright white light of his mouth stand out against the orange flames. Or perhaps... he had formed a mouth just to smile? He thought back to his observations of Grillby's face.

There were times when he could not see the white light of Grillby's mouth or a moving jawline when he spoke, so it was safe to assume the elemental’s mouth was not always visible when speaking. Which lead to the question of whether he actually _needed_ a mouth to speak, or was his voice magically projected just as his sight was?

Yet Gaster had definitely seen Grillby's mouth move in sync with vocalisations before, usually when he was smiling or grimacing or laughing or just generally expressing emotions with his mouth while he talked. So did Grillby only manifest his mouth for certain expressions, or was it simply tucked behind a pair of invisible lips, waiting to be revealed at the right moment?

And what about his lips? Were they always there or were they created on demand? Gaster knew those lips existed somehow. They were a perfect pair of lips: soft, warm, inviting... and very distracting every time he had the opportunity to affirm their existence.

Yet right now he was hard-pressed to actually spot those lips among the flickering oranges and reds of a head-shaped flame. Thus, there was no indication if his mouth was actually in there, _right now_ , as long as his lips were closed. _Schrödinger's mouth..._ Perhaps he should open the box to confirm its contents existed—

"...Gaster."

The sound of his name shook him out of his thoughts. He realised he had been staring at Grillby's invisible-perhaps-hypothetical mouth for the entire time his mind went off on a tangent and was instantly mortified.

"Sorry about that," he laughed nervously, eye lights darting to and away from the glasses that may or may not had white slits behind them. "Got carried away thinking about—" _your lips, and how I would like open them_ "—quantum mechanics."

Oh dear, that was the very opposite of smooth. He snapped his jaw shut and slapped his hands flat on the counter to stop digging himself into a hole.

If Grillby had visible eyebrows, they would surely be frowning now. All he revealed instead was a confused blue flicker of his flames. "My face made you think of... quantum mechanics?"

The skeleton shrugged. "Honestly, I don't know how my mind spun so far away."

Grillby was silent for a moment. Then, slowly and purposefully like the cat that swallowed the canary, he leaned forward and rested his arms on the bar counter, close enough that Gaster could feel the soft warmth of the elemental's flaming head against his cheekbones. The white line of his open mouth curved into a smirk. "I'd like to hear what was on your mind."

Being so close, Gaster could see past the reflections in Grillby's glasses to spot his eyes crinkling in amusement, and something else... deeper. Captivated by some unknown force, Gaster leaned forward as well.

"I was just thinking about how I’m not sure if there is always a mouth behind those lips of yours, especially when," he lowered his voice in what he hoped was a sultry tone—as sultry as he could in an accent as strange as his font, "I can barely see your lips."

"Well, having a mouth would mean there is a cavity in my head." Grillby winked again. "Let's just say I am quite adept at controlling the placement and temperature of my flames. As for my lips..." He was so close now that he only needed to whisper, "If you have trouble seeing them, perhaps you would like to check through other means if they are here or not?"

Grinning, Gaster whispered back, "I would very much like to."

And the box was opened.

**Author's Note:**

> This fic is probably a bit silly. I was thinking about how in anime and manga, there is a trope of taking off glasses in a seductive or comical manner. Like how a character would tip their glasses down to woo someone with their eyes, or their glasses get knocked off to reveal eyes squinting so hard they become two pairs of?? lips?? Anyway I thought it would be funnier if there were no eyes behind the glasses, just a blank face of fire. Then it got me thinking if Grillby as a being of fire actually needed facial features to sense the world, or did he just manifest them to let others understand his expressions, because not everyone can read the colour of his flames. Thus this silly fic and its probably inappropriate use of the Schrödinger's cat metaphor was spawned.


End file.
